Eur. Phys. J. A (2006) 27: 199-205
https://doi.org/10.1140/epja/i2005-10266-0

Hadron Physics

Partial wave analysis of πproduction in two-photon collisions at LEP

Petersburg Nuclear Physics Institute, Gatchina, Russia

^* e-mail: andsar@pnpi.spb.ru

Received: 25 November 2005
Accepted: 28 February 2006
Published online: 31 March 2006

Abstract

The reaction γγ → π⁺π^-π⁰ with quasi-real photons is studied with a total integrated luminosity of 663pb^-1, collected by the L3 detector at LEP at center-of-mass energies from 183 to 209GeV. The results of an energy-dependent partial wave analysis in the mass region 1.1≤M(π⁺π^-π⁰)≤2.2GeV are presented. The reaction is dominated by a ₂(1320) formation. A strong signal consistent with the first radial excitation of the isovector tensor state, a ₂(1700), is present and confirms the previous L3 observation. Its two-photon partial width is found to be Br(3π) = 0.37^+0.12 _-0.08keV, the relative branching ratio of ρ(770)π to f ₂(1270)π is 3.4±0.4. For all observed states the product of γγ partial width and 3π branching ratios is measured.